The above given points are good. Another idea is to use the Pulsar Charger. I have the Pulsar 2 and I have made several really good packs from a pile of older packs. Just use the matching feature on 1 cell at a time. This takes a long time, but it is well worth it in the end. If they have been sitting for a long time you may want to cycle them a few times before recording the measurements.
I came into about 5 new 18V Dewalt packs a few years back. I used the matching feature on each cell and recorded the results. I ended up with a few packs that were stronger than some "zapped" and matched packs I had spent $80 on.